Letteratura scientifica selezionata sul tema "Nitrate"
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Articoli di riviste sul tema "Nitrate"
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Mawaddah, Aida, Roto Roto e Adhitasari Suratman. "PENGARUH PENAMBAHAN UREA TERHADAP PENINGKATAN PENCEMARAN NITRIT DAN NITRAT DALAM TANAH (Influence of Addition of Urea to Increased Pollution of Nitrite and Nitrate in The Soil)". Jurnal Manusia dan Lingkungan 23, n. 3 (27 febbraio 2017): 360. http://dx.doi.org/10.22146/jml.22473.
Testo completoAbstract (sommario):
ABSTRAKNitrat dan nitrit merupakan sumber nitrogen bagi tanaman. Nitrogen sangat diperlukan tanaman untuk pertumbuhan dan perkembangan. Bentuk-bentuk nitrogen di lingkungan mengalami transformasi sebagai bagian dari siklus nitrogen seperti nitrifikasi dan denitrifikasi. Apabila kadar nitrogen dalam tanah rendah, maka urea digunakan sebagai sumber nitrogen. Perubahan urea menjadi nitrit atau nitrat pada beberapa sampel tanah perlu diketahui. Kadar nitrit dan nitrat yang tinggi dapat meningkatkan pencemaran di dalam tanah. Sampel tanah yang digunakan dalam penelitian ini adalah tanah pasir, tanah sawah, tanah pupuk kompos dan tanah pupuk kandang. Analisis nitrit dan nitrat dilakukan dengan menggunakan pereaksi asam p-amino benzoat (PABA) yang dikopling dengan N-naftiletilendiamin (NEDA) dan reduktor spongy cadmium. Sebelum digunakan untuk analisis nitrit dan nitrat, metode divalidasi terlebih dahulu. Hasil validasi metode analisis nitrit dan nitrat dengan pereaksi PABA/NEDA menunjukkan persentase perolehan kembali masing-masing antara 87,15–100,8% untuk nitrit dan 88,16–105,7% untuk nitrat. Setelah ditambah urea sebesar 0,66 g.kg-1 ke dalam tanah, konsentrasi nitrit dan nitrat pada semua sampel tanah mengalami peningkatan. Dari penelitian ini diketahui bahwa peningkatan kadar nitrit dan nitrat setelah ditambahkan urea sangat dipengaruhi oleh kondisi tanah. ABSTRACTNitrate and nitrite were sources of nitrogen for plants. Nitrogen is indispensable for the growth and development of plants. The forms of nitrogen in the environment undergoes a transformation as part of the nitrogen cycle like nitrification and denitrification. If nitrogen level in the soil is low, urea is used as a source of nitrogen. Changes of urea into nitrite or nitrate in some of soil samples need to be known. The levels of nitrite and nitrate are high can increase pollution in the soil. Some of soil samples which is used in this research were sandy soil, paddy soil, compost soil and manure soil. Analysis of nitrite and nitrate were conducted by using a reagent p-amino benzoic acid (PABA) / N-napthylethylenediamine (NEDA) and spongy cadmium as reductor. Before being used for the analysis of nitrite and nitrate, this method was validated first. The results of validation of nitrite and nitrate analysis method by using a reagents PABA / NEDA showed the percent recovery were respectively 87.15-100.8% for nitrite and 88.16-105.7% for nitrate. After the addition of 0.66 g.kg-1 urea into the soil, nitrite and nitrate concentration in all soil sample has increased. Based on this research was known that the increased levels of nitrite and nitrate after the addition of urea was influenced by soil condition.
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Bernardo, Patrícia, Luís Patarata, Jose M. Lorenzo e Maria João Fraqueza. "Nitrate Is Nitrate: The Status Quo of Using Nitrate through Vegetable Extracts in Meat Products". Foods 10, n. 12 (5 dicembre 2021): 3019. http://dx.doi.org/10.3390/foods10123019.
Testo completoAbstract (sommario):
Nitrate and nitrites are used to give the characteristic color to cured meat products and to preserve them. According to the scientific knowledge available at the moment, these compounds are approved as food additives based on a detailed ponderation between the potential risks and benefits. The controversy over nitrites has increased with the release of an IARC Monograph suggesting an association between colorectal cancer and dietary nitrite in processed meats. The trend in “clean label” products reinforced the concern of consumers about nitrates and nitrites in meat products. This review aims to explain the role of nitrates and nitrites used in meat products. The potential chemical hazards and health risks linked to the consumption of cured meat products are described. Different strategies aiming to replace synthetic nitrate and nitrite and obtain green-label meat products are summarized, discussing their impact on various potential hazards. In the light of the present knowledge, the use or not of nitrite is highly dependent on the ponderation of two main risks—the eventual formation of nitrosamines or the eventual out-growth of severe pathogens. It is evident that synthetic nitrite and nitrate alternatives must be researched, but always considering the equilibrium that is the safety of a meat product.
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KATSOULOS (Π. Δ. ΚΑΤΣΟΥΛΟΣ), P. D., N. PANOUSIS (Ν. ΠΑΝΟΥΣΗΣ) e H. KARATZIAS (Χ. ΚΑΡΑΤΖΙΑΣ). "Nitrate poisoning in ruminants". Journal of the Hellenic Veterinary Medical Society 55, n. 3 (6 dicembre 2017): 226. http://dx.doi.org/10.12681/jhvms.15098.
Testo completoAbstract (sommario):
This paper describes the nitrate - nitrite poisoning of ruminants. This disease is caused by the ingestion of large amount of nitrate salts, which are reduced in the rumen to nitrite ions. Nitrites, after their absorption, cause the formation of methemoglobin and, in turn, respiratory and circulatory distress. The aim of the treatment is to reduce the percentage of methemoglobin in blood and to stop the continuing production of nitrite ions in the rumen. For the prevention of the disease, avoidance of feedstuff rich in nitrates and improvement of the water quality, are suggested.
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Fogarasi, Erzsébet, Ibolya Fülöp, Emanuela Marcu e Mircea Dumitru Croitoru. "Presence of Nitrate and Nitrite in Well Water in Mureș County". Acta Medica Marisiensis 62, n. 1 (1 marzo 2016): 78–81. http://dx.doi.org/10.1515/amma-2015-0063.
Testo completoAbstract (sommario):
AbstractObjective: One of the most important sources of nitrite and nitrate anions, besides vegetables and meat products, is the drinking water. Presence of nitrite and nitrate in the water in higher concentrations than those set by EFSA (0.5 mg/l nitrite, 50 mg/l nitrate), may have toxicological significance. A quantitative determination of these ions in samples collected from several pleases from Mureș County was made. Methods: Ninety-seven well water samples were tested from 12 different places from Mureș County. We used a simple HPLC-UV ion pair method for the determination of nitrite and nitrate concentrations. Sensitivity of the method enables the quantification for concentrations far below the MCL value. Results: The highest amounts of nitrate and nitrite were measured in Sangeorgiu de Mureș and Cristești. Concentrations of nitrite and nitrate were exceeded in 4.12% and respectively 44.32% of the samples. Conclusions: The high amounts of nitrites and nitrates existing in well water go beyond the expected extent. This pollution can become a health risk since this water is used in human nutrition especially in child nourishment.
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Yulianti, Wina, Ima Kusumanti e Nurul Jannah. "Determination of Nitrite and Nitrate Level in Wastewater Discharge from Smoked Fish Industry". JURNAL SAINS NATURAL 12, n. 1 (27 gennaio 2022): 17. http://dx.doi.org/10.31938/jsn.v12i1.323.
Testo completoAbstract (sommario):
This research aimed to determine nitrite and nitrate contamination in wastewater discharge from the smoked fish industry around the fishpond area in Penatarsewu village, Sidoarjo East Java. Samples were taken from ten locations along The Alo River from September to November 2020. Nitrate and nitrite levels were determined by the Standard Method for Examination of Water and Wastewater 4500-NO2-B dan 4500-NO3-B. Nitrite formed a reddishpurple azo dye produced by coupling diazotized sulfanilamide with N-(1-naphthyl)-ethylene-diamine dihydrochloride after a visible spectrophotometer measured the complexes nitrite at wavelength 543 nm. Meanwhile, the Nitrate level was determined by ultraviolet spectrophotometer at a wavelength of 220 nm. The standard nitrite calibration curve was shown by the line equation y= 3,30361x-0,0028 and a determination coefficient of 0.9999. Whereas the standard nitrate was showed by the line equation y=0,2507x + 0,0067 and a determination coefficient 0,9996. The level of nitrate and nitrite in the sample ranged from 0.05-0.93mg / L 1,2-1,6 mg / L. According to a quality standard threshold value for nitrite and nitrate-based on the Government Regulation of the Republic of Indonesia (PPRI) No.82 2001 is 0,06mg/L and 10 mg/L, therefore it can be concluded that some samples are above the threshold value for nitrite level.Keywords: Alo River, nitate, nitrite, smoked fish, spectrophotometerPenentuan Kadar Nitrit dan Nitrat Pembuangan Limbah Cair Industri Ikan AsapABSTRAKPenelitian bertujuan untuk menentukan tingkat kontaminasi nitrat dan nitrit pada limbah industri ikan asap di sekitar kawasan tambak ikan asap di Desa Penatarsewu, Sidoardjo, Jawa Timur. Sampel diambil dari 10 titik di areal sekitar tambak sepanjang badan Sungai Alo pada bulan September sampai November 2020. Penentuan kadar nitrat dan nitrit mengacu pada Standard Methods for the Examination Water and Wastewater 4500-NO2-B dan 4500-NO3-B. Nitrit membentuk kompleks ungu kemerahan yang dihasilkan dari kopling sulfanilamida dengan N-(1-naptil)-etilena-diamina dihidroklorida kemudian kadarnya ditentukan dengan spektrofotometer sinar tampak pada panjang gelombang 543 nm. Kadar nitrat ditentukan menggunakan spektrofotometer ultraviolet pada panjang gelombang 220 nm. Hasil pengukuran standar nitrit menghasilkan persamaan garis y=3,30361x-0,0028 dengan koefesien determinasi 0,999 dan standar nitrat menghasilkan persamaan garis y=0,2507x+0,0067 dengan koefesien determinasi 0,9996. Kadar nitrit dan nitrat secara berturut-turut berkisar antara 0,05-0,93 mg/L dan 1,2-1,6 mg/L. Berdasarkan nilai ambang batas baku mutu nitrit dan nitrat berdasarkan Peraturan Pemerintah Republik Indonesia (PPRI) No.82 tahun 2001 adalah 0,06 mg/L dan 10 mg/L, maka dapat disimpulkan bahwa beberapa sampel mengandung kadar nitrit di atas ambang batas.Kata kunci : ikan asap, nitrat, nitrit, Sungai Alo, spektrofotometer
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McMullen, Sarah E., John A. Casanova, Lois K. Gross e Frank J. Schenck. "Ion Chromatographic Determination of Nitrate and Nitrite in Vegetable and Fruit Baby Foods". Journal of AOAC INTERNATIONAL 88, n. 6 (1 settembre 2005): 1793–96. http://dx.doi.org/10.1093/jaoac/88.6.1793.
Testo completoAbstract (sommario):
Abstract An ion chromatographic method was developed for the determination of nitrate and nitrite in vegetable and fruit baby foods. The introduction of nitrate or nitrite to food may be natural or artificial as a preservative. Because of the higher pH found in babies' stomachs, nitrate can act as a reservoir for the production of nitrite by nitrate-reducing bacteria that can be harbored in the intestinal tract. This problem does not exist in adults because of the lower pH of the adult stomach. Exposure to nitrite by infants can result in methemoglobinemia (blue baby syndrome). There are also indications that carcinogenic nitrosamines can be formed from nitrates at the higher pH. These gastric conditions disappear at approximately 6 months of age. In this method, nitrate and nitrite were separated on a hydroxide-selective anion exchange column using online electrolytically generated high-purity hydroxide eluant and detected using suppressed conductivity detection. Average recoveries of spiked nitrite residue ranged from 91 to 104% and spiked nitrate residue ranged from 87 to 104%. This method and the AOAC Official Method yield comparable results for samples containing incurred nitrate residue. In addition, this method eliminates the hazardous waste associated with the use of cadmium found in the AOAC Official Method.
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Drysdale, G. D., H. C. Kasan e F. Bux. "Assessment of denitrification by the ordinary heterotrophic organisms in an NDBEPR activated sludge sytem". Water Science and Technology 43, n. 1 (1 gennaio 2001): 147–54. http://dx.doi.org/10.2166/wst.2001.0036.
Testo completoAbstract (sommario):
The purpose of this study was to isolate and characterise the ordinary heterotrophic organisms (OHOs) present in a NDBEPR system in order to gain a better understanding of the organisms involved in denitrification as well as a more holistic and accurate evaluation of the OHO fraction attributable to denitrification in such a system. Heterotrophic bacteria were isolated from the pre- and secondary anoxic zones of the Darvill NDBEPR process and characterised according to their ability to reduce nitrates and/or nitrites under anoxic conditions. Results showed that the OHO fraction is more complex than currently accepted and, with respect to denitrification, can be more accurately subdivided into five functional groups, four of which interactively contribute to denitrification occurring in the system and one group that are non-denitrifying. These groups were defined as true denitrifiers (bacteria capable of both nitrate and nitrite reduction), incomplete denitrifiers (bacteria that reduced nitrates to nitrites with no further reduction of the nitrites produced), incomplete-nitrite reducers (bacteria capable of both nitrate and nitrite reduction, however, exhibiting severe inhibition of nitrite reduction by nitrates), exclusive nitrite reducers (bacteria only capable of reducing nitrites) and non-denitrifiers (bacteria not capable of nitrate or nitrite reduction).
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Gutyj, B., K. Leskiv, A. Shcherbatyy, V. Pritsak, V. Fedorovych, O. Fedorovych e V. Rusyn. "The influence of Metisevit on biochemical and morphological indicators of blood of piglets under nitrate loading". Regulatory Mechanisms in Biosystems 8, n. 3 (29 luglio 2017): 427–32. http://dx.doi.org/10.15421/021767.
Testo completoAbstract (sommario):
The article presents the results of research on the influence of the developed complex preparation Metisevit on the dynamics of morphological and biochemical blood indicators of piglets under nitrate loading. The research established that sodium nitrate intoxication causes disbalance of the physiological level of hematological indicators of the tested animals’ organisms. This was indicated by the manifestations of subclinical chronic nitrate-nitrite toxicosis: the increase in the level of nitrates, nitrites and methemoglobin in the blood. After prolonged feeding of the piglets with sodium nitrate at a dose of 0.3 g nitrate ion/kg, the concentration of nitrates and nitrites in the blood serum reached its maximum on the 60th day of the experiment. Also, the number of leukocytes and erythrocytes in the blood increased, and the activity of aspartate- and alanineaminotransferase in the blood serum increased. We rank the extent of liver intoxication with nitrates according to intensity of aminotransferase in the blood serum of the tested piglets. The normalization of morphological and biochemical indicators of blood of piglets under nitrate-nitrite intoxication requires usage of a preparation which contains vitamins, zeolites and antioxidants. If the fodder contains high doses of nitrates, 1.0 mg/kg dose of Metisevit is added to the fodder for preventing subclinical nitrate-nitrite toxicosis. Metisevit contains the following agents: phenozan acid, methionine, zeolite, selenium, vitamins E and C. The research conducted proved the feasibility of using Metisevit for preventing chronic nitrate-nitrite toxicosis in piglets. This preparation caused a decrease in the concentration of nitrates, nitrites and in the level of methemoglobin in the blood of piglets. Usage of Metisevit on piglets showed normalization of the number of erythrocytes and hemoglobin in the blood on the 10th day, and normalization of ASAT and ALAT on 30th and 90th days. The mechanism of Metisevit activity is connected with the direct contribution of its elements to the inhibition of the processes of absorbing metabolites which cause a toxic effect on the cell membranes of an animal’s organism. The absorbing activity of zeolite leads to decrease in concentration of agents which can be substrates for processes of peroxidation of lipids in the alimentary canal, and also to elimination of toxic pro-oxidant metabolites from the blood. This process occurs through osmosis and diffusion of these elements in the capillaries of microvilli of the small intestine and through their further fixation on sorbent granules.
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Carlsson, S., M. Govoni, N. P. Wiklund, E. Weitzberg e J. O. Lundberg. "In Vitro Evaluation of a New Treatment for Urinary Tract Infections Caused by Nitrate-Reducing Bacteria". Antimicrobial Agents and Chemotherapy 47, n. 12 (dicembre 2003): 3713–18. http://dx.doi.org/10.1128/aac.47.12.3713-3718.2003.
Testo completoAbstract (sommario):
ABSTRACT Dietary and endogenous nitrates are excreted in urine, and during infection with nitrate-reducing bacteria they are reduced to nitrite. At a low pH nitrite is converted to a variety of nitrogen oxides that are toxic to bacteria. We hypothesized that acidification of nitrite-rich infected urine would result in the killing of the nitrate-reducing bacteria. An Escherichia coli control strain and a mutant lacking nitrate reductase activity were preincubated in urine supplemented with sodium nitrate (0 to 10 mM) at pH 7.0. Then, the nitrite-containing bacterial culture was transferred (and diluted 1/10) to slightly acidic urine (pH 5 and 5.5) containing ascorbic acid (10 mM) and growth was monitored. The control strain produced nitrite in amounts related to the amount of nitrate added. This strain was killed when the culture was transferred to acidic urine. In contrast, the mutant that did not produce nitrite retained full viability. When control bacteria were grown in acidic urine with nitrate and ascorbic acid present from the start of the experiment, no inhibition of growth was noted. The MICs and minimal bactericidal concentrations of sodium nitrite-ascorbic acid in acidic urine were comparable to those of conventional antibiotics. Preincubation of nitrate-reducing E. coli in nitrate-rich urine leads to the accumulation of nitrite. Subsequent acidification of the urine results in generation of nitrogen oxides that are bactericidal. Killing, however, requires a sequential procedure in which the bacteria are first allowed to grow in a nitrate-rich neutral environment, later followed by acidification. We speculate that ingestion of nitrate followed some hours later by acidification of urine could be a new therapeutic strategy for the treatment of urinary tract infections.
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Jones, Trevor. "Nitrate/nitrite". In Practice 15, n. 3 (maggio 1993): 146–47. http://dx.doi.org/10.1136/inpract.15.3.146.
Testo completoTesi sul tema "Nitrate"
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Machado, Genikelly Cavalcanti. "Determinação sequencial de nitrato e nitrito por voltametria de pulso diferencial empregando um ultramicroeletrodo de ouro". Universidade de São Paulo, 2010. http://www.teses.usp.br/teses/disponiveis/75/75132/tde-20092010-144502/.
Testo completoAbstract (sommario):
Este trabalho descreve o desenvolvimento de um método eletroanalítico para determinação sequencial de nitrito (NO2-) e nitrato (NO3-), utilizando como técnica, a voltametria de pulso diferencial. O método se baseia na redução eletroquímica dos íons nitrato sobre um ultramicroeletrodo de ouro modificado in situ com cádmio depositado em regime de subtensão, e na seqüência, a remoção da monocamada de cádmio e a oxidação eletroquímica dos íons nitritos sobre o ultramicroeletrodo não modificado. Os ensaios voltamétricos para determinação quantitativa de nitrato e nitrito foram realizados em solução de NaClO4 0,1 molL-1 + HClO4 1,0x 10-3 molL-1 (pH = 3,3) preparada com água ultrapura. Utilizando as condições experimentais e os parâmetros voltamétricos otimizados, foram construídas curvas analíticas para determinação de nitrito e nitrato separadamente e também para determinação sequencial dos dois analitos. Para a determinação do NO2-, foi observado uma relação linear entre a corrente de pico e a concentração desse íon dentro do intervalo de concentração de 1,0 x 10-5 molL-1 a 1,1 x 10-4 molL-1, com um limite de detecção igual a 1,151 ± 0,091 µmolL-1 e limite de quantificação igual a 3,838 ± 0,091 µmolL-1. Para a determinação do NO3-, também foi observado uma relação linear entre corrente de pico e concentração desse analito dentro do intervalo estudado, que foi de 2,00 x 10-5 molL-1 a 2,50 x 10-4 molL-1. O limite de detecção encontrado foi 4,839 ± 0,275 µmolL-1 e o limite de quantificação 16,131 ± 0,275 µmolL-1. A determinação sequencial de nitrito e nitrato foi avaliada dentro do intervalo de concentração de 5,00 x 10-5 molL-1 a 2,50 x 10-4 molL-1 para NO3- e 1,00 x 10-5 molL-1 a 4,50 x 10-5 para NO2-. Para ambos os casos, a relação entre corrente de pico versus concentração do analito foi linear. Para a determinação sequencial os limites de detecção são 16,177 ± 0,794 µmolL-1 para NO3- e 2,243 ± 0,179 µmolL-1 para NO2- e os limites de quantificação são 53,922 ± 0,794 µmolL-1 para o NO3- e 7,476 ± 0,179 µmolL-1 para o NO2-. Os limites de detecção, os limites de quantificação e demais parâmetros estatísticos apresentados nesse trabalho, foram obtidos a partir de cálculos baseados em procedimentos descritos em Miller e Miller68 e Silva69.This work describes the development of an electroanalytical method for sequential determination of nitrite (NO2-) and nitrate (NO3-), using as a technique, differential pulse voltammetry. The method is based on the electrochemical reduction of nitrate ions on a gold ultramicroelectrode modified in situ by underpotential deposition of cadmium, and subsequently, the removal of cadmium monolayer and the electrochemical oxidation of nitrite on ultramicroelectrode unmodified. The voltammetric analysis for quantitative determination of nitrate and nitrite were carried out in NaClO4 0.1 molL-1 + HClO4 1.0 x 10-3 molL-1 (pH = 3.3) prepared with ultrapure water. Using the optimized experimental conditions and voltammetric parameters, analytical curves were constructed for determination of nitrite and nitrate separately and for sequential determination of the two analytes. The relationship between peak current and concentration of NO2- were found to be linear in the concentration range between 1.0 x 10-5 molL-1 and 1.1 x 10-4 molL-1, with a detection limit of 1.151 ± 0.091 µmolL-1 and quantification limit of 3.838 ± 0.091 µmolL-1. For determination of NO3- was also observed a linear relationship between peak current and concentration of analyte within the concentration range studied, which was from 2.00 x 10-5 molL-1 to 2.50 x 10-4 molL-1. The detection limit was 4.839 ± 0.275 µmolL-1 and the quantification limit was 16.131 ± 0.275 µmolL-1. The sequential determination of nitrite and nitrate was assessed within concentration range from 5.00 x 10-5 molL-1 to 2.50 x 10-4 molL-1 for NO3- and from 1.00 x 10-5 molL-1 to 4.50 x 10-5 for NO2-. In both cases, the relationship between peak current versus analyte concentration were found to be linear. The detection limits for sequential determination are 16.177 ± 0.794 µmolL-1 for NO3- and 2.243 ± 0.179 µmolL-1 for NO2- and the quantification limits are 53.922 ± 0.794 µmolL-1 for NO3- and 7.476 ± 0.179 µmolL-1 for NO2-. The detection and quantification limits and other statistical parameters presented in this work were obtained from calculations based on procedures described in Miller and Miller68 and Silva69.
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Jiquiriçá, Paulo Ricardo Ilha. "Efeitos letais e subletais da poluição por nitrogênio em larvas de anuros". Universidade de São Paulo, 2010. http://www.teses.usp.br/teses/disponiveis/41/41134/tde-13122010-144109/.
Testo completoAbstract (sommario):
As atividades humanas vêm aumentando dramaticamente a quantidade de nitrogênio inorgânico liberado nos ecossistemas, seja através da aplicação de fertilizantes na agricultura, da descarga de dejetos humanos e de seus rebanhos, ou da queima de combustíveis fósseis. Os excessos de nitrogênio são eventualmente transportados para corpos d´água, onde podem, na forma de nitrato, nitrito e amônio, atingir concentrações tóxicas para organismos aquáticos. Nesta pesquisa tive dois objetivos principais. O primeiro foi testar em laboratório a toxicidade relativa dos íons nitrato, nitrito e amônio, e a variação interespecífica na sensibilidade a esses íons, em larvas de cinco espécies de anuros (Rhinella ornata, Hypsiboas faber, Hypsiboas pardalis, Physalaemus cuvieri e Physalaemus olfersii ). Para isso utilizei bioensaios seguindo protocolos internacionalmente padronizados para testes de ecotoxicidade com organismos aquáticos, e que portanto permitem máximas reprodutibilidade e comparabilidade de resultados entre compostos, espécies, e laboratórios. No entanto, estes bioensaios carecem de realismo uma vez que simulam um cenário de exposição aguda a altas concentrações de contaminantes quando na natureza o cenário de exposição tende a ser crônico e prolongado a baixas concentrações. Além disso, bioensaios usam mortalidade como principal variável de resposta, quando também efeitos subletais podem influenciar a persistência de populações ao modular o sucesso dos indivíduos. Por isso, meu segundo objetivo foi testar em laboratório se concentrações relativamente baixas e ecologicamente relevantes de nitrato, nitrito e amônio podem afetar a sobrevivência, o crescimento, o desenvolvimento e o comportamento das larvas de R. ornata, P. cuvieri e H. faber. Demonstrei através dos bioensaios de exposição aguda que nitrato, a forma mais abundante na natureza, é de baixa toxicidade quando comparada a nitrito e amônio. Demonstrei também que há significativa variação interespecífica na sensibilidade ao nitrogênio inorgânico, e que o ranqueamento de sensibilidade das espécies ao nitrato e ao nitrito foram similares, possivelmente por conta de mecanismos comuns de ação tóxica. Através de experimentos de exposição crônica demonstrei que concentrações relativamente baixas de nitrogênio inorgânico podem causar efeitos letais e subletais às larvas de anuros se houver exposição prolongada. O nitrato causou redução no desenvolvimento larval de P. cuvieri e o amônio na sobrevivência e nas taxas de atividade nos girinos de H. faber. A exposição crônica ao nitrito também reduziu significativamente a sobrevivência das três espécies testadas, o crescimento de H. faber e as taxas de atividade de R. ornata. Contudo, é improvável que as concentrações de nitrito que manipulei em laboratório sejam comuns na natureza, especialmente em condições aeróbicas. Esta pesquisa, além de fornecer importantes informações sobre os possíveis efeitos da poluição por nitrogênio em larvas de anuros, contribui para o avanço da ecotoxicologia no Brasil ao estabelecer as bases para o emprego de espécies nativas de anfíbios como sistema-modelo experimental. Estudos futuros que almejem avaliar o risco ambiental da contaminação por nitrogênio deverão por um lado monitorar concentrações em hábitats naturais e por outro avaliar as consequências das interações sinérgicas entre nitrogênio inorgânico e outros estressores físicos, químicos ou biológicos para larvas de anfíbios.Human activities dramatically increased the amount of inorganic nitrogen released in ecosystems through the application of fertilizers in agriculture, the generation of human and livestock waste, and the combustion of fossil fuels. This nitrogen eventually reaches water bodies where it can, in the form of nitrate, nitrite and ammonium, be toxic to aquatic organisms. In this study I had two main objectives. The first was to test the relative toxicity of nitrate, nitrite and ammonium, and the interspecific variation in sensitivity to these ions, in tadpoles of five anuran species (Rhinella ornata, Hypsiboas faber, Hypsiboas pardalis, Physalaemus cuvieri and Physalaemus olfersii ). This objective was accomplished by laboratory bioassays following internationally standardized protocols for ecotoxicity tests with aquatic organisms, therefore allowing maximum reproducibility and comparability of results among compounds, species and laboratories. However, these bioassays lack realism for simulating a scenario of acute exposure to high concentrations of contaminants, while exposure in nature tends to be chronic and prolonged at low concentrations. Furthermore, bioassays use mortality as the main response variable, whereas sublethal effects may also influence the persistence of populations by modulating individual success. My second objective was therefore to test in the laboratory if low and environmentally relevant concentrations of nitrate, nitrite and ammonium affect survival, growth, development and behavior of R. ornata, P. cuvieri and H. faber larvae. Through acute exposure bioassays I demonstrated that nitrate, the most abundant N form in nature, has low toxicity when compared to nitrite and ammonium. I also demonstrated that there is significant interspecific variation in the sensitivity to inorganic nitrogen, and that the ranking of species sensitivity to nitrate and nitrite were similar, possibly due to common mechanisms of toxic action. Through chronic exposure I demonstrated that relatively low concentrations of inorganic nitrogen can cause lethal and sublethal effects on anuran larvae if there is extended exposure. Nitrate decreased developmental rate in P. cuvieri and ammonia decreased survival and activity rates in H. faber tadpoles. Chronic exposure to nitrite also significantly reduced survival of all three species tested, growth of H. faber and activity rates of R. ornata. However, it is unlikely that the concentrations of nitrite manipulated in the laboratory are common in nature, especially in aerobic conditions. This is the first study to document deleterious effects of nitrogen pollution to Brazilian amphibian species, and contributes to the development of ecotoxicology in Brazil by establishing the basis for the employment of native amphibians as model experimental system. Future studies that aim to assess the environmental risk of nitrogen contamination should monitor concentrations in natural habitats and evaluate the effects of synergistic interactions between inorganic nitrogen and other physical, chemical or biological stressors to amphibian larvae.
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Pinheiro, Lucas Cézar. "Estudo de mecanismos anti-hipertensivos do nitrito de sódio na hipertensão renovascular experimental". Universidade de São Paulo, 2014. http://www.teses.usp.br/teses/disponiveis/17/17133/tde-18032015-230532/.
Testo completoAbstract (sommario):
O NO regula diversos sistemas orgânicos. No sistema cardiovascular participa ativamente na regulação do tônus vascular entre outras funções. Disfunções na produção ou disponibilidade de NO podem comprometer sua atuação fisiológica. No âmbito vascular isto pode participar da hipertensão. Além da produção de NO pelas óxido nítrico sintases, outras vias paralela de produção fisiológica de NO a partir do nitrito tem sido descritas. O nitrito é o produto inicial da oxidação do NO, sendo posteriormente oxidado a nitrato. Sabe-se que estas três moléculas formam um ciclo dentro do organismo, onde o nitrato é excretado na saliva e convertido a nitrito pelas bactérias bucais.Este nitrito é deglutido com a saliva e exerce seus efeitos, através da conversão a NO. A conversão de nitrito a NO pode ocorrer de forma enzimática ou não enzimática. Como forma não enzimática, o nitrito é convertido a NO pela reação com H+. Esta redução ocorre principalmente no estômago. Esta tese visa elucidar possíveis mecanismos responsáveis pelos efeitos anti-hipertensivos do nitrito de sódio. Avaliamos ratos 2 rins 1 clipe (2R1C) tratados com nitrito e nitrato e verificamos os efeitos anti-hipertensivo destes. De forma Interessante, o aumento do pH gástrico com omeprazol impediu o efeito anti-hipertensivo tanto do nitrito quanto do nitrato. O omeprazol não gerou qualquer diferença na concentração plasmática de nitrito e nitrato. Foi verificado que o tratamento com nitrito e nitrato resultou em aumento das espécies nitrosiladas no plasma e este aumento foi impedido pelo omeprazol. Também testamos a influência do ciclo entero-salivar no efeito do nitrito e nitrato. Verificamos que o tratamento com enxaguante bucal levou ao bloqueio do efeito anti-hipertensivo do nitrato, mas não alterou este efeito nos animais tratados com nitrito. Em todas as abordagens experimentais o efeito anti-hipertensivo do nitrito apenas ocorreu quando houve aumento da concentração plasmática de espécies nitrosiladas.Nitric Oxide plays many functional roles in physiological systems. In the cardiovascular system it participates in a unique way in the regulation of vascular tone among other functions. Dysfunctions in the production or availability of NO may compromise their physiological activity and participate in hypertension. Besides the production of NO by the nitric oxide synthase, other physiological pathways of NO production from nitrite have been described. The nitrite and nitrate are oxidation products of NO. Further nitrite is oxidized to nitrate. These three molecules are known to forma cycle in the body. Nitrate is excreted in saliva and reduced to nitrite by oral bacteria. Nitrite then is swallowed with the saliva and exerts its effects through conversion to NO. The conversion of nitrite to NO may occur by enzymatic or non-enzymatic manner. As a non-enzymatic way nitrite is reduced to NO by reaction with H+.This reaction occurs mainly in the stomach. This thesis aims to elucidate possible mechanisms responsible for the antihypertensive effects of sodium nitrite. We studied 2K1C rats treated with nitrite and nitrate and checked anti-hypertensive effects of these molecules. The increased gastric pH by omeprazole prevented the anti-hypertensive effect of nitrite and nitrate. Omeprazole did not cause any differences in plasma nitrite and nitrate. It was found that treatment with nitrite and nitrate resulted inincreased nitrosylated species in the plasma, and this increase was blocked by omeprazole. We also tested the influence of the entero-salivarycycle effect of nitrite and nitrate. We found that treatment with mouthwash blunted the antihypertensive effect of nitrate but this effect did not change in animals treated with nitrite. Interestingly in all experimental approaches the anti-hypertensive effect of nitrite only occurred when there was an increase in the plasma concentration of nitrosylated species
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Lanza, Luciana Nunes Menolli 1981. "Tolerância ao estresse por hipóxia em soja = os efeitos do nitrato". [s.n.], 2011. http://repositorio.unicamp.br/jspui/handle/REPOSIP/315219.
Testo completoAbstract (sommario):
Orientador: Ladaslav SodekTese (doutorado) - Universidade Esstadual de Campinas, Instituto de Biologia
Made available in DSpace on 2018-08-18T18:53:51Z (GMT). No. of bitstreams: 1 Lanza_LucianaNunesMenolli_D.pdf: 7782960 bytes, checksum: 92b0ce21151564c79758f7150c4afd6d (MD5) Previous issue date: 2011
Resumo: A soja é a leguminosa de maior importância econômica no Brasil com produção de 72,23 milhões de toneladas na safra de 2010/2011. O cultivo de soja em regiões que sofrem alagamento é uma das principais causas de perda de produtividade no Brasil. Nestas condições, ocorre redução na taxa de oxigênio do solo, e o sistema radicular da planta entra em hipoxia prejudicando o desenvolvimento e a produtividade das plantas. Existem evidências de que a adição de nitrato em condições de alagamento do sistema radicular (hipoxia) promove tolerância ao estresse, entretanto os mecanismos bioquímicos que envolvem essa tolerância ainda não estão totalmente elucidados. Analisando as alterações no metabolismo de nitrogênio em hipoxia, em plantas submetidas a diferentes condições experimentais, observou-se redução do conteúdo de nitrato dentro da planta, aumento no teor de aminoácidos solúveis totais, aumento na composição dos aminoácidos livres: Ala e Gaba, e redução de Asn, em plantas não noduladas e noduladas, além de redução no conteúdo de ureídeos totais em plantas noduladas. A adição de nitrato promoveu maior conteúdo de nitrato nas raízes, seiva do xilema e nódulos, maior teor de aminoácidos solúveis totais, maior conteúdo de proteínas solúveis totais nas raízes e menor nas folhas. A atividade da enzima redutase do nitrato in vivo em condições de hipoxia reduziu nas raízes das plantas não noduladas e nas raízes e folhas das plantas noduladas. A inclusão de K15NO3 no meio demonstrou que o nitrato é, de fato, absorvido em condições de hipoxia, pois as raízes, folhas e nódulos todos incorporaram o 15N. Entretanto, absorção do nitrato sob hipoxia foi bem menor do que sob normoxia. Tanto em normoxia como hipoxia as raízes apresentaram o maior grau de enriquecimento com 15N enquanto que a incorporação nos nódulos foi menor. Houve incorporação de 15N em aminoácidos em todos os tecidos, o que permite concluir que o nitrato não é apenas absorvido pelas raízes sob hipoxia mas também assimilado e transportado para a parte aérea. Os aminoácidos mais próximos ao processo de assimilação de nitrato, Asp, Glu, Ala e Asn, foram os que mais incorporaram o 15N. No entanto, em geral um grau menor de incorporação foi encontrado sob hipoxia. A adição de nitrato, no dia 7, na solução do vaso de cinco cultivares de soja cujo sistema radicular estava alagado promoveu, na cultivar IAC Foscarin-31, maior crescimento da planta quando comparada às plantas com nitrato desde o início do experimento; na cultivar IAC-23, maior massa seca do sistema radicular; nas cultivares IAC-17 e IAC-18 foi evidenciado o mesmo crescimento da planta que as demais com nitrato; e na cultivar IAC-24, houve menor crescimento da planta. A adição também promoveu maior formação de aerênquima no caule, na raiz principal e adventícia, além de estimular a maior formação de raízes adventícias. Os dados sugerem que em condições de hipoxia, embora em quantidades bastante reduzidas e num processo mais lento, o nitrato é absorvido pelas raízes, sendo parte, convertida a aminoácidos e menos de 40% convertidos a nitrito, o qual é eliminado para o meio. A redução do nitrato via redutase do nitrato, passo inicial de sua metabolização, não é um passo limitante, uma vez que há produção de nitrito, produto da atividade da enzima. Com a adição de nitrato na solução do vaso de cinco cultivares de soja foram observadas tendências para suprir a ausência de nitrogênio e manter o desenvolvimento da plantas em condições de alagamento. A cultivar IAC Foscarin-31 e IAC-24 apresentaram crescimento geral da planta, sendo maior o crescimento observado na cultivar IAC Foscarin-31. Na cultivar IAC-23 houve maior crescimento do sistema radicular; na cultivar IAC-17, da parte aérea, assim como na IAC-18
Abstract: Soybean is a legume of great economic importance in Brazil with a production of some 72.23 million tons (2010/2011 harvest). One of the main causes of diminished yields of the cultivars produced in Brazil is their cultivation in regions subject to flooding. Under such conditions reduced availability of oxygen in the soil leads to hypoxia of the root system which impairs plant development and yield. There is evidence that the presence of nitrate during flooding can improve tolerance to hypoxic stress. However, the biochemical mechanisms underlying this phenomenon have not been fully elucidated. After analysis of the changes in nitrogen metabolism that occur under hypoxia, in plants subjected to a variety of experimental conditions, it was observed that there was a reduction in plant nitrate content, an increase in total soluble amino acids, an increase in the relative abundance of free Ala, Gaba, and a reduction in Asn, in both nodulated and non-nodulated plants, as well as a reduction of ureides in nodulated plants. The addition of nitrate during flooding resulted in a higher nitrate content of the root, nodule and xylem sap. Total soluble amino acids and soluble proteins also increased in the root under these conditions but decreased in the leaf. Under hypoxia the in vivo nitrate reductase activity declined in the roots of non-nodulated plants and in both the roots and leaves of nodulated plants. The inclusion of K15NO3 in the nutrient solution confirmed the uptake of nitrate under hypoxia, since roots, leaves and nodules became labelled. However, uptake under hypoxia was much lower than that observed under normoxia. Under both normoxia and hypoxia the roots showed the highest degree of 15N enrichment while the nodules showed the weakest. Incorporation of 15N in amino acids of all tissues shows that 15NO3 was not only taken up by the roots under hypoxia but that it was assimilated and transported to the shoot. The amino acids considered closest to N assimilation, Asp, Glu, Ala and Asn, were the most highly labelled. Nevertheless, lower levels of incorporation were generally found under hypoxia. The addition of nitrate to the hydroponic nutrient solution of five soybean cultivars, 7 days after flooding the root system, stimulated greater growth of the cultivar IAC Foscarin-31 as compared to plants with nitrate from the beginning of the experiment. It also stimulated greater root dry mass of the cultivar IAC-23, produced a similar growth increase of cultivars IAC-17 and IAC-18 compared to those with nitrate from the beginning, but resulted in less growth for the cultivar IAC-24. The addition of nitrate also stimulated formation of adventitious roots as well as aerenchyma which formed on both the stem and the main and adventitious roots. The data show that under conditions of hypoxia, nitrate is taken up by the roots although at a much lower rate than under normoxia, and in part is assimilated into amino acids while nearly 40% is reduced to nitrite which is excreted to the surrounding medium. The reduction of nitrate by the enzyme NR, the first step of nitrate metabolism, does not appear to be limiting since large quantities of the reaction product, nitrite, accumulate. With the addition of nitrate to the flooding medium of five soybean cultivars there was a tendency to overcome the absence of nitrogen and maintain plant development under flooded conditions. Of the five cultivars studied, IAC Foscarin-31 and IAC-24 responded positively through overall plant growth, with Foscarin-31 showing the greatest growth. Cultivar IAC-23 responded with greater root growth while IAC-17 and IAC-18 presented greater shoot growth
Doutorado
Biologia Vegetal
Doutor em Biologia Vegetal
5
Castro, Leonidia Maria de. "Interferência dos metais zinco, chumbo e cobre, no processo de nitrificação no tratamento de efluentes de uma indústria química: estudo de caso". Universidade de São Paulo, 2001. http://www.teses.usp.br/teses/disponiveis/18/18138/tde-27012017-162144/.
Testo completoAbstract (sommario):
Durante o estudo de um sistema de tratamento de efluentes de uma indústria química, contendo em suas águas residuárias vários metais pesados foi observada a ineficiência no processo de nitrificação do efluente tratado. Diante dessa constatação, desenvolveu-se este trabalho visando estudar as interferências dos metais pesados, Pb2+, Zn2+ e Cu2+ no desempenho do processo de nitrificação em um sistema similar de tratamento. Para observação dos efeitos dos metais Zn2+, Pb2+ e Cu2+ isoladamente, foram montados 3 reatores e simuladas as concentrações afluentes do tanque de aeração da indústria. Outros três reatores alimentados com soluções contendo Zn+Cu, Zn+Pb e Pb+Cu utilizados para observação de possíveis efeitos de sinergismo e antagonismo. Um outro reator foi alimentado com a solução dos três metais (Zn2+, Cu2+ e Pb2+). Todos os reatores, recebendo adição de metal ou não, apresentaram concentrações muito elevadas de nitrito. Na realização do ensaio de NMP ficou evidente a inibição dos organismos oxidantes de nitrito, que pode ter ocorrido pela alta concentração do próprio nitrito, ácido nitroso ou amônia livre. Efeitos dos metais Zn2+ e Cu2+ não foram evidentes, o Pb2+ foi o único metal que apresentou efeito de inibição no processo de nitrificação. Os reatores que receberam combinação de íons metálicos não evidenciaram efeitos de sinergismo nem antagonismo, sendo que o reator que recebeu adição dos três íons apresentou menor eficiência.During the study of the chemical industry effluent treatment system containing, several heavy metals, was observed an inefficiency in the nitrification process in final effluent. Therefore, this work was deve!oped to find out ofthe study of the interference of the heavy metals, Pb2+, Zn2+ and Cu2+ on the performance of nitrification process in a similar system of treatment. For observation of the effects of metals Zn2+, Pb2+ and Cu2+ separately, were established three reactors and simulate the influent concentration in the aeration tank of the industry. Other three reactors were fed with solution containing Zn+Cu, Zn+Pb and Pb+Cu for observation of possible synergism or antagonism effects. The other reactor was fed with a solution of the three metals (Zn2+, Cu2+ and Pb2+). All the reactors, receiving the addition of metaIs or not, presented very high concentrations of nitrite. In the realization of the test of NMP, the inhibition of the nitrite oxidizers organisms was evident, that might have happened due to high concentration of nitrous acid, free ammonia and nitrite. The effects of the metals Zn2+ and Cu2+ were not evident; but the Pb2+ was the only metal that presented inhibition effect in the nitrification process. The reactors that received the metallic ion combination didn\'t evidence neither synergism nor antagonism effects, however the reactor that received the addition of the three ions presented smaller efficiency.
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Melane, Pumeza. "Kinetics reactions of Ammonium Nitrate-Sodium Nitrite Reaction and Ammonium Nitrate Emulsion Explosives". Master's thesis, University of Cape Town, 2010. http://hdl.handle.net/11427/6333.
Testo completoAbstract (sommario):
The aim of this study was to understand and control the gasification rates in ammonium nitrate emulsion explosive using ammonium nitrate-sodium nitrite reaction. This reaction produces N2 gas which is the sensitizer in emulsion explosives. The NH4NO3-NaNO2 gassing reaction produces N2 gas and so the reaction could be followed by the pressure increase in a closed reaction vessel. The reaction is pH sensitive, so the role of pH was investigated in the pH range 2 to 5. Gasification reactions for unbuffered NH4NO3-NaNO2 reaction were found to be rapid below pH = 3 and maximum pressure was attained within 2 hours of starting the reaction. At pH = 4.5 and 5 the reaction failed to attain maximum pressure. Initial rate of reaction showed sensitivity to pH, the rate of reaction decreasing with increasing pH. The reaction was found to be second order with respect to nitrite species. The effects of three different buffers (potassium hydrogen phthalate, sodium formate and sodium citrate) were also investigated. At pH = 3 pressure traces for the buffered reactions had attained maximum pressure while at pH = 3.5 only sodium citrate buffer had reached a pressure stable state. The presence of the buffers resulted in a lower overall pressure change and absolute pH change and higher rate constants and initial rate of reaction than in their absence. iv A Lewis acid (Zinc Nitrate) was added to the buffered and unbuffered NH4NO3-NaNO2 reactions to investigate a patent claim that addition of a Lewis acid would increase the rate of reaction. The presence of zinc nitrate in the buffered reactions resulted in rapid pressure increase; higher initial rate of reactions than the unbuffered with zinc nitrate. Ammonium nitrate solution was emulsified resulting in an ammonium nitrate emulsion explosive and kinetics of gasification was investigated. The gasification reactions were found to be rapid at pH 3.2, slowing significantly with increased pH as indicated by initial rates of reaction and as predicted by the gasification reaction rate law. Maximum pressure increase was attained within three hours at pH 3.2, whereas reactions conducted at pH 4.0 and 4.5 failed to reach maximum pressure even after 24 hours as evidenced by plots of pressure versus time. The effect of buffers in the ammonium nitrate emulsions was also investigated.
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Fletgen, Marie Christine. "Le devenir des nitrates et des nitrites dans l'organisme humain et leur danger potentiel : problème des nitrosamines". Paris 5, 1992. http://www.theses.fr/1992PA05P241.
Testo completo
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Hüsler, Bruno R. "Nitrite/nitrate status in veal calves: effects of feeding nitrite, nitrate, arginine, and iron and of endotoxin administration /". [S.l.] : [s.n.], 1999. http://www.stub.unibe.ch/html/haupt/datenbanken/diss/bestell.html.
Testo completo
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Melchert, Wanessa Roberto. "Desenvolvimento de procedimentos analíticos limpos em sistemas de análises em fluxo para determinação de espécies de interesse ambiental". Universidade de São Paulo, 2005. http://www.teses.usp.br/teses/disponiveis/46/46133/tde-20102006-084230/.
Testo completoAbstract (sommario):
A química limpa tem como principal objetivo o desenvolvimento e a implementação de processos e produtos químicos para reduzir ou eliminar o uso ou a geração de substâncias nocivas à saúde humana e ao meio ambiente. Neste trabalho, foram desenvolvidos procedimentos analíticos limpos para a determinação de nitrato e nitrito em águas naturais e para o tratamento dos resíduos gerados na determinação espectrofotométrica de nitrito e fenóis. Para tanto, foram exploradas as principais estratégias empregadas em química limpa: substituição dos reagentes tóxicos, minimização do consumo dos reagentes e dos resíduos gerados e tratamento desses resíduos. O procedimento analítico limpo para a determinação de nitrato em águas naturais foi baseado em medidas diretas no ultravioleta, após separação de nitrato dos interferentes utilizando um sistema de análises em fluxo com coluna de resina aniônica. O método desenvolvido emprega um único reagente (HClO4) em quantidades mínimas (18 µL/determinação) e permite a determinação de nitrato entre 0,50 e 25,0 mg L-1, sem interferência de ácido húmico, NO2-, PO43-, Cl-, SO42- e ferro(III) nas quantidades usuais em águas naturais. A freqüência de amostragem e o coeficiente de variação (n = 20) foram estimados em 17 determinações h-1 e 0,7%, respectivamente. Os resultados obtidos para amostras de águas de diferentes procedências foram concordantes com o método de referência (redução a nitrito por limalhas de cádmio cobreado seguida por reação de diazo-acoplamento) a nível de confiança de 95%. O tratamento do resíduo gerado na determinação de nitrito, empregando irradiação (UV) na presença do reagente de Fenton (80 mmol/L H2O2 e 1 mmol/L Fe2+), promoveu completa descoloração do resíduo com diminuição de ca. 87% na concentração de carbono orgânico total. A fotodegradação também foi aplicada no tratamento do resíduo gerado na determinação de fenóis totais com 4-aminoantipirina. A degradação ocorreu na presença de H2O2 e irradiação (UV). A completa supressão da absorção de radiação pela 4-aminoantipirina foi observada após 30 min de recirculação da solução no foto-reator, à vazão de 4 mL/min. O procedimento analítico para a determinação de nitrito foi baseado em sistema de análises em fluxo com multicomutação empregando mini-bombas solenóides para o gerenciamento das soluções. O sistema foi acoplado a um foto-reator para a degradação em linha dos resíduos gerados. O método desenvolvido minimiza as quantidades de reagentes (0,6 mg sulfanilamida e 0,03 mg N-naftil-etilenodiamina por determinação) e permite a determinação de nitrito entre 0,10 e 1,00 mg L-1 (r = 0,998) com sensibilidade comparável à alcançada no procedimento com adição contínua de reagentes. O limite de detecção (99,7% de confiança), coeficiente de variação (n = 20) e freqüência de amostragem foram estimados em 17 µg L-1, 2,6% e 80 determinações h-1, respectivamente.Green chemistry has as principal objective the development and implementation of chemical processes and products to minimize or eliminate the use or generation of harmful substances to the human health and the environment. In this work, clean analytical procedures for determination of nitrate and nitrite in natural waters and for the treatment of wastes generated in the spectrophotometric determination of nitrite and phenol were developed. The principal strategies employed in green chemistry were explored to achieve these goals: replacement of the toxic reagents, minimization of reagent consumption and waste generation and waste treatment. The clean analytical procedure for nitrate determination in natural waters was based on the direct spectrophotometric measurement in the ultraviolet, after separation of nitrate from interfering species in a flow-injection system with an anion-exchange resin. The developed method employ only one reagent (HClO4) in minimum amount (18 µL/determination) and can be applied for nitrate determination within 0.50 and 25.0 mg L-1, without interference of humic acid, NO2-, PO43-, Cl-, SO42- and iron(III) in concentrations typically found in natural waters. The sampling rate and the coefficient of variation (n = 20) were estimated as 17 determinations per hour and 0.7%, respectively. Results obtained for natural water samples of different origin were in agreement with the reference method (reduction to nitrite by copperized cadmium filings followed by a diazo-coupling reaction) at the 95% confidence level. The treatment of the waste generated in nitrite determination employing UV irradiation in the presence of Fenton reagent (80 mmol/L H2O2 and 1 mmol/L Fe2+) caused the complete discoloration of the waste and reduced the total organic carbon concentration in 87%. The photodegradation was also applied for the treatment of the waste generated in the determination of total phenols with 4-aminoantipyrine. The degradation occurred in the presence of H2O2 and UV irradiation. Radiation absorption by 4-aminoantipyrine was completely suppressed after 30 min of treatment of solution in the recirculation mode at 4mL/min. The analytical procedure for nitrite determination was based on a flow system with multicommutation employing solenoid micro-pumps for the solution handling. The developed method minimizes the reagent amounts (0.6 mg sulfanilamide and 0.03 mg N-(1-Naphthyl)-ethylene-diamine per determination) and can be applied for nitrite determination within 0.10 and 1.00 mg L-1 (r = 0.998) with sensitivity comparable to the achieved in the procedure with continuous reagent addition. The detection limit (99.7% of confidence), coefficient of variation (n = 20) and sampling rate were estimated as 17 µg L-1, 2.6% and 80 determinations per hour, respectively.
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Ferreira, Paulo Eduardo Gomes. "Efeito de um programa pré-operatório de fortalecimento supervisionado da musculatura inspiratória na evolução hospitalar de pacientes submetidos a operações cardíacas". Universidade de São Paulo, 2013. http://www.teses.usp.br/teses/disponiveis/17/17137/tde-05042013-230022/.
Testo completoAbstract (sommario):
Introdução: A disfunção respiratória é uma das complicações mais frequentes após operações cardíacas. Vários fatores contribuem para que as disfunções respiratórias ocorram, dentre eles está a disfunção da musculatura inspiratória que, por sua vez, pode ser multifatorial. Objetivo: O condicionamento da musculatura inspiratória no período pré-operatório poderia ajudar a reduzir a incidência de complicações respiratórias no pós-operatório de operações cardíacas. Métodos: No presente trabalho 21 pacientes voluntários, de ambos os sexos, com idade mínima de 50 anos, com fraqueza de musculatura inspiratória e candidatos à operação de revascularização cirúrgica do miocárdio e/ou operação valvar cardíaca no Hospital das Clínicas da Faculdade de Medicina de Ribeirão Preto-USP foram distribuídos aleatoriamente em 2 grupos. Em um grupo, 10 pacientes foram submetidos a um período mínimo de 9 dias de treinamento da musculatura inspiratória utilizando um incentivador respiratório marca Threshold® IMT (Respironics, Cedar Grove, NJ, EUA), com carga de 40, 60 e 80% da pressão inspiratória máxima. Os outros 11 pacientes receberam apenas orientações gerais, sem treinamento objetivo da musculatura respiratória. Comparamos os valores espirométricos antes e após o treinamento dentro de cada grupo. A evolução da pressão inspiratória máxima, da pressão expiratória máxima e da gasometria arterial de ambos os grupos, antes e após o treinamento, bem como a sua evolução temporal no pós-operatório, além dos valores de nitrito/nitrato no condensado do exalado pulmonar. Comparamos também a evolução clínica de ambos os grupos. Resultados: Observamos que o treinamento causou elevação significativa do pico de fluxo expiratório (p=0,028) e diminuição nos valores de nitrito/nitrato no condensado do exalado pulmonar (p=0,05) e redução das complicações pós operatórias (p=0,057), sendo as duas últimas não significativas. Todavia, não houve diferença na evolução gasométrica e nem da pressão inspiratória máxima ou da pressão expiratória máxima entre ambos os grupos. Conclusão: O treinamento da musculatura respiratória inspiratória em pacientes internados, além de factível e seguro, resulta em maior fortalecimento dessa musculatura, reduz a morbidade pós-operatória e os níveis de nitrito/nitrato no condensado do exalado pulmonarIntroduction: Respiratory dysfunction is one of the most common complications after cardiac operations. Several factors contribute to respiratory dysfunctions that occur among them is inspiratory muscle dysfunction that, in turn, may be multifactorial. Objective: The conditioning of inspiratory muscles on preoperative could help reduce the incidence of respiratory complications in the postoperative period of cardiac operations. Methods: In this study 21 patients volunteers of both sexes, aged 50 years, with weakness of inspiratory muscles and candidate operation of CABG and / or heart valve surgery at the Hospital of the Medical College of Ribeirão Preto-USP were randomized into 2 groups. In one group, 10 patients underwent a minimum of 9 days of inspiratory muscle training using an incentive spirometry \"Threshold® IMT\" (Respironics, Cedar Grove, NJ, USA) with a load of 40, 60 and 80% of maximal inspiratory pressure. The other 11 patients received only general guidelines without respiratory muscle training goal. We compared spirometric values before and after training within each group. The evolution of maximal inspiratory pressure, maximal expiratory pressure and arterial blood gas analysis of both groups before and after training, as well as its temporal evolution postoperatively, and the values of nitrite / nitrate in exhaled breath condensate. We also compared the clinical outcomes in both groups. Results: We observed that the training caused significant peak expiratory flow (p=0,028) and decrease in nitrite/nitrate in exhaled breath condensate (p=0,05) and reduction of postoperative complications (p=0,057), the last two being non-significant. However, there was no difference in blood gas evolution nor maximal inspiratory pressure and maximal expiratory pressure between both groups. Conclusion: The inspiratory muscle training in patients hospitalized, and feasible and safe, results in further strengthening these muscles, reduces postoperative morbidity and levels of nitrite / nitrate in exhaled breath condensate
Libri sul tema "Nitrate"
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Bryan, Nathan S., e Joseph Loscalzo, a cura di. Nitrite and Nitrate in Human Health and Disease. Totowa, NJ: Humana Press, 2011. http://dx.doi.org/10.1007/978-1-60761-616-0.
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Bryan, Nathan S., e Joseph Loscalzo, a cura di. Nitrite and Nitrate in Human Health and Disease. Cham: Springer International Publishing, 2017. http://dx.doi.org/10.1007/978-3-319-46189-2.
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Loscalzo, Joseph, e Nathan S. Bryan. Nitrite and nitrate in human health and disease. New York: Humana Press, 2011.
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Imperial Cancer Research Fund (Great Britain). Nitrate, nitrite and nitroso compounds in human cancer. A cura di Forman David, Shuker David e Shuker David E. G. Oxford, U.K: Published for the Imperial Cancer Research Fund by Oxford University Press, 1989.
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International Agency for Research on Cancer e World Health Organization, a cura di. Ingested nitrate and nitrite, and cyanobacterial peptide toxins. Lyon, France: International Agency for Research on Cancer, 2010.
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Tsadilas, Christos. Nitrate Handbook. New York: CRC Press, 2021. http://dx.doi.org/10.1201/9780429326806.
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Bogárdi, Istvan, Robert D. Kuzelka e Wilma G. Ennenga, a cura di. Nitrate Contamination. Berlin, Heidelberg: Springer Berlin Heidelberg, 1991. http://dx.doi.org/10.1007/978-3-642-76040-2.
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E, Rezaković Dženana, e Alpert Joseph S, a cura di. Nitrate therapy & nitrate tolerance: Current concepts and controversies. Basel: Karger, 1993.
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Edmundson, William. The Nitrate King. New York: Palgrave Macmillan US, 2011. http://dx.doi.org/10.1057/9780230118799.
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Alahi, Md Eshrat E., e Subhas Chandra Mukhopadhyay. Smart Nitrate Sensor. Cham: Springer International Publishing, 2019. http://dx.doi.org/10.1007/978-3-030-20095-4.
Testo completoCapitoli di libri sul tema "Nitrate"
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Makkar, Harinder P. S., P. Siddhuraju e Klaus Becker. "Nitrate and Nitrite". In Plant Secondary Metabolites, 33–39. Totowa, NJ: Humana Press, 2007. http://dx.doi.org/10.1007/978-1-59745-425-4_7.
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Ware, George W. "Nitrate and Nitrite". In Reviews of Environmental Contamination and Toxicology, 117–30. New York, NY: Springer New York, 1988. http://dx.doi.org/10.1007/978-1-4684-7083-3_10.
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Bellucci, Elisa Rafaela Bonadio, Camila Vespúcio Bis Souza, José Manuel Lorenzo, Gonzalo Aleu, Alfredo Teixeira, Rubén Domínguez e Andrea Carla da Silva-Barretto. "Nitrate and Nitrite". In Methods to Assess the Quality of Meat Products, 85–95. New York, NY: Springer US, 2022. http://dx.doi.org/10.1007/978-1-0716-2002-1_8.
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Bryan, Nathan S. "Inorganic Nitrate and Nitrite". In Nitrate Handbook, 357–73. New York: CRC Press, 2021. http://dx.doi.org/10.1201/9780429326806-21.
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Klurfeld, David M. "Nitrite and Nitrate in Cancer". In Nitrite and Nitrate in Human Health and Disease, 263–78. Totowa, NJ: Humana Press, 2011. http://dx.doi.org/10.1007/978-1-60761-616-0_16.
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Klurfield, David M. "Nitrite and Nitrate in Cancer". In Nitrite and Nitrate in Human Health and Disease, 311–23. Cham: Springer International Publishing, 2017. http://dx.doi.org/10.1007/978-3-319-46189-2_21.
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Hotchkiss, Joseph H., Michael A. Helser, Chris M. Maragos e Yin-Ming Weng. "Nitrate, Nitrite, andN-Nitroso Compounds". In ACS Symposium Series, 400–418. Washington, DC: American Chemical Society, 1992. http://dx.doi.org/10.1021/bk-1992-0484.ch033.
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Lück, Erich, e Martin Jager. "Nitrate". In Chemische Lebensmittelkonservierung, 90–94. Berlin, Heidelberg: Springer Berlin Heidelberg, 1995. http://dx.doi.org/10.1007/978-3-642-57868-7_9.
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Lück, Erich. "Nitrate". In Chemische Lebensmittelkonservierung, 78–82. Berlin, Heidelberg: Springer Berlin Heidelberg, 1986. http://dx.doi.org/10.1007/978-3-642-96924-9_11.
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Bailey, Stephen J., Anni Vanhatalo e Andrew M. Jones. "Nitrate and Exercise Performance". In Nitrite and Nitrate in Human Health and Disease, 293–310. Cham: Springer International Publishing, 2017. http://dx.doi.org/10.1007/978-3-319-46189-2_20.
Testo completoAtti di convegni sul tema "Nitrate"
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Ciorba, Petru, Elena Zubcov, Nina Bagrin e Liliana Teodorof. "Dynamics of mineral nitrogen compounds in the waters of the Dniester River". In Xth International Conference of Zoologists. Institute of Zoology, Republic of Moldova, 2021. http://dx.doi.org/10.53937/icz10.2021.13.
Testo completoAbstract (sommario):
This article presents the results of studying the content of mineral (ammonium ions, nitrites and nitrates) and organic nitrogen compounds in water samples collected from the Dniester river in 2020. In the study are examines the seasonal dynamics of the forms of mineral nitrogen, total nitrogen and the correlation between organic and mineral nitrogen. Limits of ammonium ion concentration in the Dniester river varied between 0.002 mg N/l and 0.93 mg N/l, nitrite ions 0.002 mg N/l and 0.05 mg N/l, nitrate ions 0.002 mg N/l - 1.36 mg N/l.
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Bradshaw, Robert W., Joseph G. Cordaro e Nathan P. Siegel. "Molten Nitrate Salt Development for Thermal Energy Storage in Parabolic Trough Solar Power Systems". In ASME 2009 3rd International Conference on Energy Sustainability collocated with the Heat Transfer and InterPACK09 Conferences. ASMEDC, 2009. http://dx.doi.org/10.1115/es2009-90140.
Testo completoAbstract (sommario):
Multi-component molten salts have been formulated recently that may enhance thermal energy storage for parabolic trough solar power plants. This paper presents further developments regarding molten salt mixtures consisting of common alkali nitrates and either alkaline earth nitrates or alkali nitrite salts that have advantageous properties for applications as heat transfer fluids in parabolic trough systems. We report results for formulations of inorganic molten salt mixtures that display freeze-onset temperatures below 100°C. In addition to phasechange behavior, several properties of these molten salts that significantly affect their suitability as thermal energy storage fluids were evaluated, including chemical stability and viscosity. The nitrate-based molten salts have demonstrated chemical stability in the presence of air up to 500°C. The capability to operate at temperatures up to 500°C may allow an increase in maximum temperature operating capability vs. organic fluids in existing trough systems and will enable increased power cycle efficiency. Experimental measurements of viscosity were performed from near the freeze-onset temperature to about 200°C. Viscosities can exceed 100 cP near the freezing temperature but are 4 to 5 cP in the anticipated operating temperature range. Experimental measurements of density, thermal conductivity and heat capacity are in progress and will be reported at the meeting. Corrosion tests were conducted for several thousand hours at 500°C with stainless steels and at 350°C for carbon and chromium-molybdenum steels. Examination of the specimens demonstrated good compatibility of these materials with the molten nitrate salt mixtures. Laboratory studies were conducted to identify mixtures of nitrate and nitrite (NO2−) salts as additional candidates for a low-melting heat transfer fluid. Mixtures in which the cations were potassium, sodium and lithium, in various proportions, demonstrated freezing points as low as 70°C for a particular nitrate/nitrite anion composition. Development has emphasized mixtures that minimize lithium content in order to reduce the cost as the lithium salt is the most expensive constituent. Work is in progress to explore the phase diagram of the 1:1 mol ratio of nitrate/nitrite and to evaluate physical properties such as viscosity, density and thermal conductivity. Results to date indicate that the viscosity of these mixtures is considerably less than nitrate-only melts, which necessarily contain calcium cations to suppress freezing to similarly low temperatures.
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Sallom, Audai, e A. E. Khadzhidi. "METHOD FOR REMOVING NITRATES FROM WATER WATER SUPPLY SYSTEMS". In STATE AND DEVELOPMENT PROSPECTS OF AGRIBUSINESS Volume 2. DSTU-Print, 2020. http://dx.doi.org/10.23947/interagro.2020.2.180-182.
Testo completoAbstract (sommario):
To remove nitrates from the water of water supply systems, the polyvinyl / chitosan compound (PVA / CS) was studied. Optimal conditions for the absorption of nitrates on PVA / CS were investigated using antisurfaces. The results of the study showed that the mixture of polymers PVA / chitosan CS is an effective absorbent material for removing nitrates from water: the maximum concentration of solid phase nitrate was 0.5 mg / g at a pH in the range from 3 to 6; contact time was 70 minutes at a dose of adsorbent 2 g / l. These conditions were applied to the study of the equilibrium and kinetic adsorption of nitrates on (PVA / CS). Adsorption data are described by Langmuir and Freindlich models. The maximum concentration of solid phase nitrate calculated by the Langmuir model for (PVA / CS) was 92.59 mg / L. Nitrate mobility was analyzed on pseudo-adsorbents of the second pseudo-class, this relates to the nature of chemical adsorption.
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Goreacioc, Tatiana, Maria Sandu, Raisa Nastas e Anatolie Tarita. "Poluarea apelor de suprafata şi subterane cu compuşi ai azotului". In Impactul antropic asupra calitatii mediului. Institute of Ecology and Geography, Republic of Moldova, 2019. http://dx.doi.org/10.53380/9789975330800.21.
Testo completoAbstract (sommario):
In this paper the situation of pollution with nitrogen compounds both in the EU member states and in the Republic of Moldova was analyzed. Also, the existing methods of determination of nitrate ions are analyzed and the necessity of elaborating the method for determination of the nitrate ions in the presence of nitrite ions.
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AlOudah, Yahya. "Waste Management Control by Applying Novel Method for HPLC Technique to Replace SKALAR Cadmium Reduction Method for Nitrate and Nitrite in Water Analysis". In International Petroleum Technology Conference. IPTC, 2022. http://dx.doi.org/10.2523/iptc-22291-ea.
Testo completoAbstract (sommario):
Abstract A new method was developed on High Performance Liquid Chromatography (HPLC) instrument equipped with a Photodiode Array UV detector to determine the Nitrite-Nitrogen and Nitrate-Nitrogen in seawater, industrial wastewater, and groundwater at very low concentrations. This HPLC used a reverse phase system with polar mobile phase and nonpolar C-18 Column. The split mechanism of the HPLC Chromatography was accomplished by employing acetonitrile and acidified water with pH 2.5, at 55:45 ACN: H2O v/v as a mobile phase, long HPLC Column (C-18, 0.5 μm, 250 × 4.6 mm) and at 1 mL/min flow rate. The calibration curves of nitrate-nitrogen and nitrite-nitrogen in the range of 0.05 to 1.0 mg/L were exceptionally linear with correlation coefficients greater than 0.999 and with low Method Detection Limit (MDL) of 0.02 mg/L for both of NO2-n and NO3-n. This developed method also showed comparable results to the ones obtained by the traditional SKALAR instrument which follows ASTM D3867 Automated Cadmium Reduction Method. The results of the nitrate-n and nitrite-n for the Quality Control Samples (QCS) and the average recoveries percentage of the spiked samples demonstrated high accuracy values 99.20% - 101.40% & 98.4% - 99.1% respectively. The very low detection limit is what set this study apart from the previous conducted studies on nitrate and nitrite determination by HPLC. This new developed method is safer and with minimal cost compared to the traditional cadmium reduction method. It doesn't consume water, or require preparation of many hazardous reagents that contain and generate cadmium wastes.
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Martin, Richard Lloyd. "Corrosion Consequences of Nitrate/Nitrite Additions to Oilfield Brines". In SPE Annual Technical Conference and Exhibition. Society of Petroleum Engineers, 2008. http://dx.doi.org/10.2118/114923-ms.
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Foy, B. R., P. C. Dell'Orco, E. Wilmanns, R. McInroy, J. Ely, J. M. Robinson e S. J. Buelow. "REDUCTION OF NITRATE AND NITRITE SALTS UNDER HYDROTHERMAL CONDITIONS". In Physical Chemistry of Aqueous Systems: Meeting the Needs of Industry. Connecticut: Begellhouse, 2023. http://dx.doi.org/10.1615/icpws-1994.770.
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Frunza, Gabriel. "Research on methods of processing raw materials of plant origin with a view to reducing nitrate substances". In Simpozion stiintific al tinerilor cercetatori, editia 20. Academy of Economic Studies of Moldova, 2023. http://dx.doi.org/10.53486/9789975359023.24.
Testo completoAbstract (sommario):
Recently, in the agricultural industry, in order to increase the amount of harvest, organic and inorganic fertilizers are used, due to which in the plant food products they are contaminated with high concentrations of nitrates, which can bring them to simple limbs of the limbs and face. until the onset of cancer. This research was created to determine the concentration of nitrates in certain fruits and vegetables and to find out some methods to reduce the concentration of nitrates in foods and which methods are more effective in lowering the concentration of nitrites. Following the research, 3 processes were performed to reduce the nitrate concentration. The methods given were 1 storage in the refrigerated state of 2 fruits and 2 vegetables in the results of which a decrease in the concentration of nitrates was obtained from 8% to 31% depending on the product and 2 methods of processing products such as washing with water. within 2 hours for which as object of study were 8 products the most representative results being the decrease by 46.62% for tomatoes and 48.78% for grapes. The other methods are heat treatment and more precisely the boiling and frying of 2 products (potato and carrot), the results of which are presented as the increase of nitrates in boiling products which is due to the displacement of nitrates inside the product to the boiling and frying. nitrates up to 82.56% for carrots and 62.15% for potatoes.
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Mohamed-Said, M., B. Cowe, A. Bertoncello, F. Oliveira-Martinez e L. Galliot. "The Use of Artificial Intelligence (AI) to Give Insight to a Complex Well Tubing Issue to Ensure Suitable Corrosion Mitigation Approaches". In ADIPEC. SPE, 2023. http://dx.doi.org/10.2118/216617-ms.
Testo completoAbstract (sommario):
Abstract In one of TotalEnergies North Sea fields, nitrate is continuously injected as the main mitigation of reservoir souring. The nitrate treatment is employed to limit the biogenic generation of H2S, due to reservoir souring. Reservoir souring is caused by the proliferation of SulfateReducing microbes (bacteria and/or archaea). In parallel, severe corrosion was observed in oil producing well tubing conveying fluids from a reservoir subjected to nitrate treatment. It is known that nitrates can catalyze the corrosion of carbon steels through different mechanisms, in particular electrochemical or microbiological. The challenge was therefore to accurately evaluate the impact of nitrate injection, and its presence in the produced fluids, on the corrosion of the producing well tubing. The influence of nitrate treatment towards corrosion of carbon steel well tubing has been singled out using an artificial intelligence algorithm. The algorithm employs a method called "Propensity Score Matching" (PSM). PSM is a statistical method commonly used in the medicine field to assess the efficiency of treatment in biased data. This method has been used to compare two reservoirs, one being subjected to nitrate treatment and another that has never been subjected to nitrate treatment. In this paper a first known use of causal inference in industrial settings is presented. It helped removing biases by comparing only comparable data and to find causal relationship in the data. Outcomes of the multi-faceted study have led to optimized corrosion mitigation approaches and increased well tubing service life.
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Fiore, Marina, Massimo Brenci e Janusz Kozlowski. "Fiber optic sensor to detect nitrite and nitrate in water". In Environmental Sensing III, a cura di Robert A. Lieberman. SPIE, 1997. http://dx.doi.org/10.1117/12.276145.
Testo completoRapporti di organizzazioni sul tema "Nitrate"
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Hobbs, D. T. Evaluation of nitrate and nitrite destruction/separation technologies. Office of Scientific and Technical Information (OSTI), agosto 1997. http://dx.doi.org/10.2172/573703.
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Van Rijn, Jaap, Harold Schreier e Yossi Tal. Anaerobic ammonia oxidation as a novel approach for water treatment in marine and freshwater aquaculture recirculating systems. United States Department of Agriculture, dicembre 2006. http://dx.doi.org/10.32747/2006.7696511.bard.
Testo completoAbstract (sommario):
Ammonia waste removal in recirculating aquaculture systems is typically accomplished via the action of nitrifying bacteria in specially designed biofilters that oxidize ammonia to produce nitrate. In the majority of these systems nitrate is discharged to the environment through frequent water exchanges. As environmental considerations have made it necessary to eliminate nitrate release, new strategies for nitrate consumption are being developed. In the funding period we showed that ammonia removal from wastewater could take place by an anaerobic ammonia oxidation process carried out by bacterial Planctomycetessp. Referred to as “anammox”, this process occurs in the absence of an organic source and in the presence of nitrite (or nitrate) as an electron acceptor as follows: NH₃ + HNO₂ -> N₂ + 2H₂O. Annamox has been estimated to result in savings of up to 90% of the costs associated with was wastewater treatment plants. Our objective was to study the applicability of the anammox process in a variety of recirculating aquaculture systems to determine optimal conditions necessary for efficient ammonia waste removal. Both seawater and freshwater systems operated with either conventional aerobic treatment of ammonia to nitrate (USA) or, in addition, denitrifying biofilters as well as anaerobic digestion of sludge (Israel) were tested. Molecular tools were used to screen and monitor different treatment compartments for the presence of Planctomycetes. Optimal conditions for the enrichment of the anammox bacteria were tested using laboratory scale biofilters as well as a semi-commercial system. Enrichment studies resulted in the isolation of some unique heterotrophic bacteria capable of plasmid-mediated autotrophic growth in the presence of ammonia and nitrite. Our studies have not only demonstrated the presence and viability of Planctomycetes spp. in recirculating marine and freshwater systems biofilter units but also demonstrated the applicability of the anammox process in these systems. Using our results we have developed treatment schemes that have allowed for optimizing the anammox process and applying it to recirculating systems.
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Congdon, J. W. Effect of Nitrite/Nitrate concentrations on Corrosivity of Washed Precipitate. Office of Scientific and Technical Information (OSTI), marzo 2001. http://dx.doi.org/10.2172/781032.
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Burger, L. L., e R. D. Scheele. The reactivity of cesium nickel ferrocyanide towards nitrate and nitrite salts. Office of Scientific and Technical Information (OSTI), settembre 1991. http://dx.doi.org/10.2172/5293537.
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Upadhyaya, Shrini K., Abraham Shaviv, Abraham Katzir, Itzhak Shmulevich e David S. Slaughter. Development of A Real-Time, In-Situ Nitrate Sensor. United States Department of Agriculture, marzo 2002. http://dx.doi.org/10.32747/2002.7586537.bard.
Testo completoAbstract (sommario):
Although nitrate fertilizers are critical for enhancing crop production, excess application of nitrate fertilizer can result in ground water contamination leading to the so called "nitrate problem". Health and environmental problems related to this "nitrate problem" have led to serious concerns in many parts of the world including the United States and Israel. These concerns have resulted in legislation limiting the amount of nitrate N in drinking water to 10mg/g. Development of a fast, reliable, nitrate sensor for in-situ application can be extremely useful in dynamic monitoring of environmentally sensitive locations and applying site-specific amounts of nitrate fertilizer in a precision farming system. The long range objective of this study is to develop a fast, reliable, real-time nitrate sensor. The specific objective of this one year feasibility study was to explore the possible use of nitrate sensor based on mid-IR spectroscopy developed at UCD along with the silver halide fiber ATR (i.e. attenuated total internal reflection) sensor developed at TAU to detect nitrate content in solution and soil paste in the presence of interfering compounds. Experiments conducted at Technion and UCD clearly demonstrate the feasibility of detecting nitrate content in solutions as well as soil pastes using mid-IR spectroscopy and an ATR technique. When interfering compounds such as carbonates, bicarbonates, organic matter etc. are present special data analysis technique such as singular value decomposition (SYD) or cross correlation was necessary to detect nitrate concentrations successfully. Experiments conducted in Israel show that silver halide ATR fiber based FEWS, particularly flat FEWS, resulted in low standard error and high coefficient of determination (i.e. R² values) indicating the potential of the flat Fiberoptic Evanescent Wave Spectroscopy (FEWS) for direct determinations of nitrate. Moreover, they found that it was possible to detect nitrate and other anion concentrations using anion exchange membranes and M1R spectroscopy. The combination of the ion-exchange membranes with fiberoptices offers one more option to direct determination of nitrate in environmental systems.
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Cox, J. L., M. A. Lilga e R. T. Hallen. Thermochemical nitrate reduction. Office of Scientific and Technical Information (OSTI), settembre 1992. http://dx.doi.org/10.2172/7077253.
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Mickalonis, J. I. Corrosion of steel in simulated waste containing different nitrate and nitrite concentrations. Office of Scientific and Technical Information (OSTI), luglio 1993. http://dx.doi.org/10.2172/10177023.
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ADAS, RSK. Nitrate Surveillance Monitoring Program (Annual Report May 2021 - March 2022). Food Standards Agency, dicembre 2022. http://dx.doi.org/10.46756/sci.fsa.uau489.
Testo completoAbstract (sommario):
Every Member State is required to monitor and report levels of nitrate in specified foodstuffs as part of the European Commission regulation and the UK also requires this information as part of the collection of data to support the review of retained EU law in the UK and inform the setting of policy around maximum nitrate levels. The requirement to carry out monitoring for nitrate in lettuce, spinach and rocket is being met by the UK Nitrate Surveillance Programme. Results are presented for the period between 1st April 2021 and 31st March 2022. A total of 202 samples were collected within the sampling period, comprising of 130 lettuce, 9 rocket, 26 spinach samples. A further 37 samples categorised at “Other Green Leafy Vegetables”, which comprised of samples including mustard, mizuna, celery, Pak Choi and cabbage. The lowest average nitrate concentration was recorded in summer-grown iceberg lettuce (935.2 mg/kg), and no iceberg samples exceeded the maximum nitrate concentration. The highest average nitrate concentration was seen in winter grown non-iceberg lettuce grown under protection within the lettuce group (3242.2 mg/kg), and in winter-grown rocket overall (4271.2 mg/kg). The number of samples exceeding the maximum threshold increased this year to 7 samples – 2 samples of open-air non-iceberg lettuce sampled in the summer, 1 sample of protected non-iceberg lettuce in the summer, and 3 samples of spinach. A further 4 samples were within 10% of the maximum threshold. Consistent with previous years of this project, a strong correlation was found between nitrate concentration and sampling date, with samples collected later in the season showing greater concentrations, indicating potential interactions between nitrate accumulation and climate – particularly light levels and available soil moisture and the accumulation of nitrate in the soil through subsequent fertiliser applications with successive planting. Furthermore, there was significant interaction between nitrate accumulation, product type and cultivation type, which could be further explored to better identify risk factors associated with nitrate accumulation in leafy vegetables grown in the UK.
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Ladd-Lively, Jennifer L. Uranyl Nitrate Flow Loop. Office of Scientific and Technical Information (OSTI), ottobre 2008. http://dx.doi.org/10.2172/939393.
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Sadergaski, Luke, e Travis Hager. Measuring Hydroxylammonium, Nitrate and Nitrite Concentration with Raman spectroscopy for 238Pu Supply Program. Office of Scientific and Technical Information (OSTI), agosto 2021. http://dx.doi.org/10.2172/1819552.
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